Abstract

Inflammatory response induced cell apoptosis plays a crucial role in the pathological process of secondary injury in spinal cord injury (SCI), and targeted reduction of secondary inflammatory response can effectively promote neuronal recovery after SCI. TRIM32, an E3 ubiquitin ligase, has been shown to modulate inflammation by influencing ubiquitination modifications. In this study, we sought to investigate the function of TRIM32 in the progression of SCI. LPS treated PC12 cells and SD rats were utilized to establish the SCI model. HE staining and BBB score was conducted to analyze the SCI development of rats. The inflammatory factor contents were detected using ELISA kits. Cell growth was analyzed by CCK-8 and flow cytometry assays. Western blot was performed to detect ubiquitination levels and protein levels. In addition, CO-IP assay was carried out to analyze the relationship between TRIM32 and TLR4. TRIM32's ubiquitination modification of TLR4 is achieved through K48 linkage. TRIM32 was down-regulated in the LPS treated PC12 cells and SCI rats. Overexpression of TRIM32 decreased the IL-1β, IL-6, and TNF-α contents in vivo and in vitro. Additionally, TRIM32 overexpression increased the ubiquitination levels of TLR4, which further decreased the protein stability and expression of TLR4. TRIM32's ubiquitination modification of TLR4 is achieved through K48 linkage. Furthermore, the overexpression of TLR4 counteracted the influence of TRIM32 on cell viability, the rate of apoptosis, and the levels of IL-1β, IL-6, and TNF-α in PC12 cells subjected to LPS treatment. In rats with SCI, the upregulation of TRIM32 alleviated damage to spinal cord tissues and enhanced the BBB scoring. This study demonstrated that TRIM32 overexpression inhibited the inflammation in SCI progression through inducing the ubiquitination degradation of TLR4. TRIM32 might be an intriguing host therapeutic target for the treatment of SCI.